1. Field of the Invention
The present invention relates to a laundry dryer, and more particularly, to a laundry dryer and a rear plate for a drum thereof enabling to apply a rear plate of a drum to an electric laundry dryer and a gas type laundry dryer in common.
2. Discussion of the Background Art
Generally, a laundry dryer is installed separately from a washer so as to dry wet laundry automatically after completion of washing.
An example of such a laundry dryer is schematically illustrated in FIG. 1, and a background art laundry dryer is explained by referring to FIG. 1 as follows.
Referring to FIG. 1, an opening 1a is formed at a front of a case 1 so as to put in or remove laundry, and the opening is closed or opened by a door 2.
A drum 30 in which inputted laundry is dried is rotatively installed inside the case 1, and a driving motor 4 generating a turning force is installed at a lower part of the drum 30. A pulley 5 and a belt 6 are connected between the driving motor 4 and drum 30 so as to transfer turning power to the drum 30.
The drum 30 includes a cylindrical drum body 31 of which both sides are open, a front plate 33 coupled with a front portion of the drum body 31 and having a laundry input opening 33b at a central portion, and a rear plate 35 coupled with a rear portion of the drum body 31.
An inlet hole 35a is formed at the rear plate 35 of the drum 30, and an inlet duct 10 guiding external air inside the drum 30 is coupled with the inlet hole 35a. A heater 8 is installed at an entrance of the inlet duct 10 so as to heat the air introduced through an air intake lb of the case 1 into hot and dry air.
An outlet hole 33a is formed at the front plate 33, and an outlet duct 9 guiding air discharged from the drum 30 to the outside is coupled with the outlet hole 33a. A blow fan 7 driven by the driving motor 4 is installed inside the outlet duct 9 so as to make the air in the drum 30 flow forcibly.
Numerals xe2x80x98Cxe2x80x99 and xe2x80x98Fxe2x80x99 in FIG. 1 indicate a laundry and a filter, respectively.
Operation of the laundry dryer according to the background art is carried out as follows.
A user opens the door 2, puts wet laundry C and the like inside the drum 30 through the opening 1a, and then pushes a start button to actuate the driving motor 4 so that the driving motor 4 rotates to generate a turning force. The turning force of the driving motor 4 is then transferred to the drum 30 through the pulley 5 and belt 6 so as to rotate the body 31 of the drum 30. Hence, the laundry C inside the drum 30 is mixed.
Simultaneously, the blow fan 7 is actuated to rotate so as to make the external air flow into the drum 30 through the inlet duct 10 and inlet hole 35a. In this case, the suctioned air is heated by the heater 8 and changed into a very dry and hot air having very low humidity. The drum is supplied with the dry and hot air to dry the laundry C inside the drum 30.
Moreover, the dry air inside the drum 30 comes into contact with the wet laundry to remove the humidity from the laundry, and then is discharged outside the case 1 through the outlet duct 9. In this case, the filter F removes pile, waste thread, and the like from the discharge air.
Drying performance of such a laundry dryer depends mostly on the active contact between the wet laundry C and the dry air flowing inside the drum 30. Various study and research teaches that a factor having the biggest influence on a flow of the dry air passing through the drum 30 is the position and shape of the inlet hole 35a formed at the rear plate 35.
The position of the inlet hole 35a formed at the rear plate 35 according to the background art and a structure of the inlet duct 10 connected to the inlet hole 35 are explained by referring to FIG. 2 and FIG. 3 as follows.
Referring to FIG. 2, the rear plate 35 has a disk shape, and the inlet hole 35a is formed at a left upper position of the rear plate 35.
Referring to FIG. 3, the inlet duct 10 is constructed with a pair of plates 11 and 12 assembled with each other so as to form a path for the dry air. An entrance 11c is formed at a lower portion of the inlet duct 10 to make hot air flow in by being coupled with the heater 8, and a plurality of duct holes 11a are formed at an upper portion of the inlet duct 10 to correspond to the inlet hole 35a of the rear plate 35.
A total open area of the duct holes 11a is generally formed to cover about 40% of the open area of the inlet hole 35A.
When the inlet hole 35a is formed at the upper position of the rear plate 35, as shown in FIG. 4, the air drawn inside the drum 30 tends to flow in a direction having a least airflow resistance and the wet laundry tends to be distributed at a lower part of the drum. Hence, the air drawn inside the drum 30 flows as having a speed component preponderating toward about 45xc2x0 upper side for the rotating axis of the drum 30.
Accordingly, the hot and dry air drawn inside the drum 30 fails to be contacted with the wet laundry C actively so as to be discharged through the outlet duct 9. Thus, the laundry drying time increases and energy efficiency decreases.
The inlet hole 35a in the laundry dryer according to the background art is positioned at the upper portion of the rear plate 35, thereby becoming disadvantageous with regard to drying performance.
In spite of such disadvantages, the reason why the inlet hole 35a is designed to be located at the upper portion of the rear plate 35 is as follows.
Generally, laundry dryers are divided into an electrical laundry dryer and a gas type laundry dryer in accordance with the form of using the heater 8. The electrical laundry dryer includes an electric hot wire for heating air, while the gas type laundry dryer includes a nozzle jetting a gas so that the air is heated in a manner that the jetted gas reacts with suctioned air for combustion.
Specifically, the gas type laundry dryer should secure at least a predetermined length of the inlet duct 10 for the characteristics of combustion. If the sufficient length of the inlet duct 10 fails to be secured, a flame reaches the inside of the drum 30 so as to cause damage on the laundry C or set it on fire.
For the above safety reasons, the gas type laundry dryer, as shown in FIG. 4, should form the inlet hole 35A at the upper portion of the rear plate 35. Yet, the electrical laundry dryer does not need the long combustion section like the gas type, so therefore the length of the inlet duct 10 can be shortened and the inlet hole 35a is installed at the lower portion of the rear plate 35. Hence, the electrical laundry dryer enables to improve the drying performance.
As mentioned through FIG. 1 to FIG. 4, when the positions of the inlet holes 35a of the electrical and gas type laundry dryers are set up at the upper portions of the rear plates 35, the same rear plate shown in FIG. 2 can be used regardless of the species of the laundry dryers. Besides, the inlet ducts 10 having different shapes in part are used only case by case. Namely, the inlet duct 10 can be used for both the electrical and gas type laundry dryers. Nevertheless, a vent 11b (as a plurality of air paths), as shown in FIG. 3, is added to the inlet duct 10 to dilute the burnt air.
When the inlet hole 35a is formed equivalently at the upper portion of the rear plate 35, the inlet duct 10 manufactured differently in accordance with the electrical or gas type can be assembled with the same rear plate 35 by the same assembly process so as to reduce a product cost of the laundry dryer. As such, it is impossible to increase the drying performance of the electrical laundry dryer any more.
On the contrary, if the position of the inlet hole 35a is adjusted to fit the characteristics of the electrical or gas type laundry dryer, the product cost of the laundry dryer increases.
Namely, if the inlet hole 35a of the electrical laundry dryer is installed at the lower portion of the rear plate 35 in order to improve the drying performance, the position of the inlet hole 35A is different from that of the gas type laundry dryer. Hence, the rear plates 35 for the electrical and gas type laundry dryers should be manufactured using expensive large moldings. Moreover, the inlet ducts 10 applied to the electrical and gas type laundry dryers differ in length, thereby requiring different designs to be manufactured.
Unfortunately, when the position of the inlet hole 35a of the electrical laundry dryer is different from that of the gas type laundry dryer, the rear plates 35 and inlet ducts 10 should be manufactured separately as well as assembled using different assembly lines, respectively. Hence, a product cost of the laundry dryer increases greatly.
Accordingly, the present invention is directed to a laundry dryer and rear plate for a drum thereof that substantially obviates one or more problems due to limitations and disadvantages of the background art.
An object of the present invention is to provide a laundry dryer and a rear plate for a drum thereof enabling to apply a rear plate of a drum to an electric laundry dryer and a gas type laundry dryer in common so as to improve productivity of the laundry dryer as well as reduce product costs.
Another object of the present invention is to provide a laundry dryer and rear plate for a drum thereof enabling to cope with a modification of a position of a hole, through which hot and dry air flows inside a drum, in accordance with design requirements such as drying capacity change of the drum, airflow capacity change of a blowing fan, and the like.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a laundry dryer according to the present invention includes a drum body rotatively installed inside a case, a rear plate coupled so as to cover a rear portion of the drum body and having an inlet hole open from upper to lower sides across upper and lower areas centering around a horizontal line of the rear plate, and an inlet duct connected to the inlet hole of the rear plate so as to guide air to flow inside the drum body wherein the air dries the laundry.
Preferably, a ratio L/D between an upper and lower opening length L of the inlet hole and an outer diameter D of the rear plate is at least 0.45.
Preferably, a covering portion is formed at an end portion of the inlet duct in a flowing direction of the air so as to cover the inlet hole of the rear plate and wherein a plurality of duct holes are formed at the covering portion so that the air passes through the duct holes to flow inside the drum body.
More preferably, an opening area of the inlet hole is at least 375% of a total opening area of the duct holes.
More preferably, an electrical heater heating the air using an electrical coil is installed at an entrance of the inlet duct and wherein the duct holes are distributed on a relatively lower area in the covering portion.
More preferably, the duct holes are distributed in the lower area centering around the horizontal line of the rear plate.
More preferably, a gas type heater heating the air using gas combustion is installed at an entrance of the inlet duct and wherein the duct holes are distributed on a relatively upper area in the covering portion.
More preferably, the duct holes are distributed in the upper area centering around the horizontal line of the rear plate.
More preferably, the covering portion has the same shape of the inlet hole so as to be inserted into the inlet hole for coupling.
Preferably, the inlet hole is positioned at one area centering around a vertical center line of the rear plate.
In another aspect of the present invention, a laundry dryer including a drum rotatively installed inside a case, a heater heating an air flowing inside the drum, a rear plate coupled so as to cover a rear portion of the drum and having an inlet hole open long from upper to lower sides across upper and lower areas centering around a horizontal line of the rear plate, and an inlet duct covering the inlet hole and simultaneously having a plurality of duct holes formed at a portion covering the inlet hole so as to guide the air heated by the heater to flow inside the drum.
Preferably, a ratio L/D between an upper and lower opening length L of the inlet hole and an outer diameter D of the rear plate is at least 0.45.
Preferably, an opening area of the inlet hole is at least 375% of a total opening area of the duct holes.
Preferably, the heater is an electrical type and the duct holes are distributed on the lower area centering around the horizontal line of the rear plate.
Preferably, the heater is a gas type and the duct holes are distributed on the upper area centering around the horizontal line of the rear plate.
Preferably, the inlet hole extends from upper to lower sides across the upper and lower areas centering around the horizontal line of the rear plate to be coupled with an inlet duct guiding airflow inside the drum.
More preferably, a ratio L/D between an upper and lower opening length L of the inlet hole and an outer diameter D of the rear plate is at least 0.45.
More preferably, the inlet hole is covered with a covering means having a plurality of duct holes and an opening area of the inlet hole is at least 375% of a total opening area of the duct holes.
More preferably, the duct holes are distributed on one of the upper and lower areas centering around the horizontal center line of the rear plate.
More preferably, the inlet hole is positioned at one area centering around a vertical center line of the rear plate.
The laundry dryer according to the present invention has the inlet hole connected to the rear plate of the drum from the upper side to the lower side, whereby the identical rear plate can be applied to the electrical laundry dryer using the inlet duct having the duct holes at the lower side or the gas type laundry dryer using the other inlet duct having the duct holes at the upper side.
The present invention has the rear plate for common use, whereby the rear plate need not be manufactured additionally in accordance with the species of the laundry dryer, i.e. electrical or gas type laundry dryer. Therefore, the present invention enables to manufacture the rear plate used for the electrical or gas type laundry dryer for common use using the same metal mold.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.